Automatically deploying and retracting covers for hauling vehicle compartments are well represented in the prior art. In the case of trailers and railroad cars, the covering canopy is often supported by a series of spaced apart rigid bows spanning the top of the compartment from side to side. The ends of each bow usually ride along a pair of guiding rails secured to top parts of the hauling compartment as exemplified by the apparatus disclosed in U.S. Pat. No. 3,820,840 Forsberg incorporated herein by reference.
If the compartment sides and their attached guiding rails are not absolutely parallel as often seen in long railroad cars, jamming may occur during deployment or retraction of the canopy.
Jamming can also result from debris entering the guiding rails during loading or unloading of the cargo compartment.
The instant invention provides an elegant and practical way to palliate these conditions.